The present invention relates to a motor driven hand tool and, more particularly, to a motor driven hand tool, especially an oscillating grinder, which comprises a hand tool housing, an oscillator work tool carrier mounted on the hand tool housing, at least one elastic supporting member connected to the hand tool housing to hold the work tool carrier on the hand tool housing, the at least one elastic supporting member having at least one approximately rod-like spring element.
A motor driven hand tool of this type is described in German Patent Document DE 93 20 393 U1. One piece elastic supporting members directly or indirectly connected to the work tool carrier are provided in this motor driven hand tool, which prevent the work tool carrier from falling off or prevent rotation. These supporting members include front and rear oscillating elements, of which the front has four individual oscillating columns and the rear has three individual oscillating columns, which are connected in one-piece by an upper transverse member. Because of that the individual supporting members each nearly have a T-shape. The individual oscillating columns each form an approximately rod-shaped spring element, which is loaded with compression force in a direction along its rod-like body and transverse force acting across that direction. The supporting members hold the oscillating work tool carrier in the housing, so that the work tool carrier can perform an orbital motion by means of an eccentric when it is driven.
The one-piece structure of the supporting member provides the disadvantage that the form of the hand tool regarding the location of the supporting member, the form of the work tool carrier, the form of the hand tool housing and the like, are limited. Furthermore this leads to additional limitations of the possible embodiments for the supporting members. The hand tool has the additional disadvantage that the work tool carrier in one-piece with the supporting members and/or a part of the hand tool connected with it must be replaced when the supporting member or members are damaged. Because of the rod shape of the individual spring elements they are in a position to take compression forces and at the same time transverse forces and to hold the work tool carrier fixed in the housing with a predetermined spacing in the rod longitudinal direction along the spring elements only because of that.
Elastic supporting members in the form of approximately column-like cylindrical parts for holding the work tool carrier in the housing are included in other motor driven hand tools which are described in German Patent Document DE 38 05 926 A1. These supporting members are formed as rubber connectors with a waist in the vicinity of their longitudinal center (as in DE 40 38 634 A1) or this elastic member has a transverse filling at one end so that at least a weak S-shaped behavior results (EP 404 133 S2). Primarily the elastic supporting member fits in the housing at one end and in a cup-like recess in the work tool carrier at the other end, so that the supporting member can be changed or replaced in case of damage. Because of the form of the elastic material the supporting members thus formed have damping properties so that vibrations are damped and the hand tool runs more smoothly because of these damping properties. It is disadvantageous however to form the supporting members from elastic material because the deformability of these supporting members is comparatively strong and responsive. It is also disadvantageous that elastic supporting members do not permit geometrically precise positioning of the work tool carrier and because of that an expensive positioning and mounting of the drive shaft with increased costs is required. Furthermore elastic supporting members lead to power losses because of their deformability that must be compensated by a greater motor power.